排序方式： 共有10条查询结果，搜索用时 78 毫秒
1
1.
The paper describes the results of an experimental study on the behavior of cover stones on a liquefiable soil bed exposed to a progressive wave. The soil was silt with d50 = 0.098 mm. Stones, the size of 4 cm, were used as cover material. The effect of packing density of stones, and that of number of stone layers (including the effect of an intermediate filter layer) were investigated. Pore pressure was measured across the soil depth. The experiments show that the soil liquefaction depended mainly on two parameters: the packing density of stones, and the number of stone layers. When the liquefaction occurs, stones sink in the soil. Mechanisms of liquefaction and sinking are described, and practical guidelines are recommended. 相似文献
2.
Hydrogeochemistry,environmental isotopes and the origin of the Hamamayagi-Ladik thermal spring (Samsun,Turkey) 总被引：3，自引：3，他引：0
Hamamayagi thermal spring (HTS) is located along the North Anatolian Fault Zone. The thermal spring has a temperature of 36°C,
with total dissolved solids ranging from 485.6 to 508.5 mg/L. Hard, brittle, and gray limestones Permian aged are the reservoir
rocks of the HTS. δ18O–δ2H isotope ratios clearly indicate a meteoric origin for the waters. The δ34S value of sulfate in the thermal water is nearly 4.1‰ and implies a diagenetic environment characterized by reduced sulfur
compounds. The δ13C ratio for dissolved inorganic carbonate in the HTS lies between −1.78 and −1.62‰, showing that it originates from the dissolution
of fresh-water carbonates. Quartz geothermometry suggests a reservoir temperature of 52–85°C for the Hamamayagi geothermal
field, but chalcedony geothermometers suggest reservoir temperatures between 30 and 53°C. 相似文献
3.
Wave boundary layer over a stone-covered bed 总被引：1，自引：0，他引：1
This paper summarizes the results of an experimental investigation on wave boundary layers over a bed with large roughness, simulating stone/rock/armour block cover on the sea bottom. The roughness elements used in the experiments were stones the size of 1.4cm and 3.85cm in one group of experiments and regular ping-pong balls the size 3.6cm in the other. The orbital-motion-amplitude-to-roughness ratio at the bed was rather small, in the range a/ks = 0.6–3. The mean and turbulence properties of the boundary-layer flow were measured. Various configurations of the roughness elements were used in the ping-pong ball experiments to study the influence of packing pattern, packing density, number of layers and surface roughness of the roughness elements. The results show that the friction factor seems to be not extremely sensitive to these factors. The results also show that the friction factor for small values of the parameter a/ks does not seem to tend to a constant value as a/ks → 0 (contrary to the suggestion made by some previous investigators). The present friction-factor data indicates that the friction factor constantly increases with decreasing a/ks. An empirical expression is given for the friction factor for small values of a/ks. The results further show that the phase lead of the bed friction velocity over the surface elevation does not seem to change radically with a/ks, and found to be in the range 12°–23°. Furthermore the results show that the boundary-layer turbulence also is not extremely sensitive to the packing pattern, the packing density, the number of layers and the surface roughness of the roughness elements. There exists a steady streaming near the bed in the direction of wave propagation, in agreement with the existing work. The present data indicate that the steady streaming is markedly smaller in the case where the ping-pong balls are aligned at 45° to the wave direction than in the case with 90° alignment. Likewise, it is found that the steady streaming is relatively smaller in the case of the one-layer ping-pong-ball roughness than in the case of the two-layer situation. 相似文献
4.
The paper describes the results of an experimental study on the behaviour of a submerged rock berm in liquefied backfill soil. The soil is liquefied by waves, and the rock berm is subject to the orbital motion of the liquefied soil. The soil used in the experiments was silt with d50=0.075 mm. Various berm materials were used, stones of size 0.74-2.5 cm, plastic balls of size 3.6 cm, brass of size 2.5 cm and steel of size 1.0 cm. The experiments show that rock berms that are stable under very large waves can be unstable when they are exposed to the motion of liquefied soil. The limited data obtained in the study were plotted as a function of the mobility number versus the Keulegan-Carpenter number for the range of the Reynolds number of the tests. The critical mobility number corresponding to the incipient motion of the berm stones is determined. Recommendations are made as to how the present findings can be implemented in practice. 相似文献
5.
6.
In the region between Mersin and Tarsus cities, located along the Mediterranean Sea coast in southern Turkey, the demand for groundwater has increased dramatically as the available surface water supplies have already been developed. Fundamental information is required to characterize the existing groundwater system in this area in order to establish a sustainable groundwater-use policy. For this purpose, hydrochemical and environmental isotopic data were collected and integrated with available geological and hydrogeological information to develop a conceptual model of the system. Results, backed up mainly by depleted stable isotope composition and infinitesimal tritium content, suggest that most of the groundwater along the coastal zone is supplied by the neighboring mountain belt while local precipitation has also contributes to aquifer recharge. The validation of the conceptual perspective by a steady-state numerical groundwater flow model reveals that about 90% of the recharge to the aquifer system is supplied by the deep flow of karstic groundwater fed from the Taurus Mountains. Monitoring of changes in the recharge regime of the mountain sector seems to be critical in establishing future groundwater use policies. 相似文献
7.
Lin Li Craig H. Benson Tuncer B. Edil Bulent Hatipoglu 《Geotechnical and Geological Engineering》2008,26(2):177-187
A case history is described where Class C fly ash was used to stabilize recycled pavement material (RPM) during construction
of a flexible pavement in Waseca, MN, USA. The project consisted of pulverizing the existing hot-mix asphalt (HMA), base,
and subgrade to a depth of 300 mm to form RPM, blending the RPM with fly ash (10% by dry weight) and water, compacting the
RPM, and placement of a new HMA surface. California bearing ratio (CBR), resilient modulus (Mr), and unconfined compression (qu) tests were conducted on the RPM alone and the fly ash stabilized RPM (SRPM) prepared in the field and laboratory to evaluate
how addition of fly ash improved the strength and stiffness. After 7 days of curing, SRPM prepared in the laboratory had CBR
ranging between 70 and 94, Mr between 78 and 119 MPa, and qu between 284 and 454 kPa, whereas the RPM alone had CBR between 3 and 17 and Mr between 46 and 50 MPa. Lower CBR, Mr, and qu were obtained for SRPM mixed in the field relative to the SRPM mixed in the laboratory (64% lower for CBR, 25% lower for
Mr, and 50% lower for qu). In situ falling weight deflectometer testing conducted 1 year after construction showed no degradation in the modulus of
the SRPM, even though the SRPM underwent a freeze–thaw cycle. Analysis of leachate collected in the lysimeter showed that
concentrations of all trace elements were below USEPA maximum contaminant levels. 相似文献
8.
Hesham El Ganainy M. Melih Demirkan Juan Jose Gutierrez Raghav Ramanathan Bulent Hatipoglu Mazen Elias Adib Daniel Barton 《Geotechnical and Geological Engineering》2016,34(1):125-141
Karst cavities in fissured soluble rock represent serious geotechnical hazard for civil construction and urban development. The process of cavity formation, expansion, and propagation is difficult to predict because it is driven by a combination of diverse causes, such as the dissolution rate of rock; flow of groundwater; amount of fine material within rock layers; presence of loose, uncontrolled fill over the rock; and the leakage of underground utilities. Several factors can affect cavity stability, including cavity geometry and dimensions, cavity depth, overburden surface-layer lithology, and surface-loading conditions. This paper presents a case study for karst cavities stability in the Abu Dhabi Municipality (ADM) of the United Arab Emirates as part of a comprehensive study initiated by the ADM to address the geotechnical, geologic, and hydrogeological hazards encountered in the municipality. The purpose of this study is to develop a methodology for assessing karst cavities stability in the ADM, and thereby, quantify their potential hazard for civil construction and urban development in the municipality. A numerical study is performed, using a finite difference model that is based on site-specific ground conditions encountered in a localized area. Results from this numerical investigation are presented in the form of stability charts for different lithologic and surface-loading conditions. These charts are used to develop a set of geographic information system cavity-collapse geohazard maps for the study area to factor solution cavity-collapse risk into an integrated geohazard map for the ADM. Based on available information and the case study presented herein, it is concluded that the collapse of solution cavities do not significantly contribute to the geotechnical hazard observed in the ADM. 相似文献
9.
Records from South America show that modern ENSO (El Nino-Southern Oscillation) did not exist 7000 cal yr B.P. and has developed progressively since then. There has been little information available on oceanic conditions in the eastern equatorial Pacific (EEP) to constrain explanations for ENSO onset. We report quantitative observations on thermocline and mixed-layer conditions in the EEP during ENSO start up. We found important changes in both the thermocline and the mixed layer, indicating increased upwelling of cooler waters since 7000 cal yr B.P. This resulted from change in the source and/or properties of waters supplying the Equatorial Undercurrent, which feeds upwelling along the equator and the Peru margin. Modeling shows that ENSO is sensitive to subsurface conditions in the eastern equatorial Pacific and that the changes in the thermocline we observed were driven by extratropical processes, giving these a role in conditioning the development of ENSO. This is in contrast to models that call for control of equatorial Pacific oceanography by tropical processes only. These infer stronger upwelling and cooler surface waters for the EEP during the mid-Holocene, which is not supported by our results. 相似文献
10.
The flow around a cylinder, surface mounted or partly buried has been examined at Reynolds number of 1.3×104 and 2.6×104 by using the flow visualization method in the case of steady current. The lengths of the upstream and downstream separation regions were determined and the characteristics of the flow area were discussed for the cylinder having different burial depth to the diameter ratio (G/D). For comparsion, some numerical results obtained from the application of the FLUENT, computational fluid dynamics (CFD) software package have also been presented. Both experimental and numerical results indicated that the lengths of the separation regions near the upstream and downstream of the cylinder decreased with the increasing burial ratio (G/D=0, 0.20, 0.50). The results have significant implications both for the illustration of the potential for using CFD software and highlighting the need for data of two dimensional flow around the buried cylinder. 相似文献
1